Connector for flat cables

Abstract: An electrical connector (1 ) has multiple contacts (40) arranged in an insulating housing (10) at a predetermined pitch and each having a J-shaped connecting section (44). When an external force (F), which tends to pull a flat cable (4) in a direction away from the connector (1) is applied to the flat cable (4), the connecting sections (44) of all the contacts (40) are bent and their back surfaces (56) are pressed against the inner wall (30) of the insulating housing (10). This pressure generates resistance from the inner wall (30) resulting in a strong frictional force between the connecting sections (44) and the flat cable (4), thus reliably securing the cable (4) in the connector housing (10).

Description: This invention relates to electrical connectors for flat cables and, more especially, to connectors with multiple contacts intended for attachment to the ends of flexible flat cables (FFC or FPC). FFC-type cables are highly flexible, have multiple conductors and are extraordinarily convenient in work and versatile in application. Therefore, FFC-type cables and related connectors are widely used in such home electronic devices as compact-disk players and video cameras and in such office equipment as copiers and facsimile machines. There is a number of connectors offered for use with FFC cables, for example, the connectors described in Japanese Utility Model No. 64 (1989)-13682. In such conventional connectors for cables, connections are generally made by inserting the end of the FFC cable and the extension of a slider between one beam-shaped contact and the inner wall of the insulating housing. However, because of the necessity to use sliders, such connectors for the cables become rather large and have many parts, which is inconsistent with the latest requirements toward the reduction in dimensions and the cost of electronic equipment. In addition, since the insertion of the FFC cable using the slider can be done with little or without any insertion force, its retention force in the connector depends entirely on the elasticity of the beam-shaped contact and, as a rule, the retention force is rather low. EP-A-0519317 discloses a board edge connector for connecting a flat flexible cable with a printed circuit board. In this connector, one of a pair of terminals is retained against the upper wall of a terminal mounting space and has a cantilever contact beam extending form its front end in the direction of insertion of the flexible cable. Another terminal is retained on the bottom wall of the terminal mounting space and is bent forwardly and upwardly. The two terminals contact both upper and lower surfaces of the flexible cable at different locations from the front or cable insertion end of the connector housing. The purpose of this invention is to provide a connector for flat cables which alleviates the above mentioned problems associated with conventional connectors for FFC cables and which is easy to manufacture, provides for easy connection, has a small number of parts and small dimensions, and is characterized by a high cable-retention force. The invention consists in an electrical connector for an electrical cable, comprising an insulating housing with an opening for receiving the electrical cable and slots for receiving electrical contacts, and at least one electrical contact having a connecting section projecting from a base section, said connecting section being received in one of the slots and having an end portion comprising a free end portion directed back towards the base section and into the opening for contacting the cable, characterised in that the contact includes a stabilizing section projecting from the base section and inserted into another slot in order to secure the base section with respect to the housing, and in that the connecting section extends into said one slot in spaced relation with an inner wall thereof and is resiliently deflectable such that, upon insertion of the electrical cable into the opening in the housing, said resilient connecting section is engageable at its free end portion with the electrical cable and is deflectable in a direction away from said cable and, upon attempted separation of the cable from the housing, said end portion of the resilient connecting section is engageable at the same time with said inner wall and the electrical cable thereby resisting removal of the electrical cable from the housing. Conveniently, the resilient connecting section is generally J-shaped. Hence, when a flat cable is inserted into the opening in the insulating housing designed to receive such a cable and to the position where it comes into contact with the free end portion of the connecting section of the contact, when subsequently a force is applied in the direction to pull the cable out, the back side of the J-shaped section of the connecting section is deflected and forced against the inner wall of the housing. The frictional force between the flat cable and the J-shaped section of the connecting section increases with increase in the pulling force, thus providing a reliable retention of the cable in the connector. Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:- Figs. 1-3 show an embodiment of a connector for flat cables according to the instant invention, where Fig. 1 is a front view, Fig. 2 is a bottom view, and Fig. 3 is a cross-sectional view along the 3-3 line indicated in Fig. 2. Fig. 4 is a cross-sectional view of a connector for flat cables similar to the one shown in Fig. 3 and showing the status when a flat cable is in the process of insertion into the connector shown in Fig. 1. Fig. 5 is a cross-sectional view of the connector for flat cables as shown in Fig. 4, but which shows the status of the connector when a flat cable is pulled from the connector shown in Figs. 1-3. Fig. 6 shows another embodiment of the connector for flat cables according to this invention; shown along the same cross-sectional view as in the Fig. 4. Connector 1 for flat cables (FFC) consists of a rectangular insulating housing 10 and a number of contacts 40 (in this specific case 10 contacts) arrayed along a longer side of the housing 10. Opening 14 for receiving the flat cable is made in surface 12 of the insulating housing 10 in a longitudinal direction. In addition, primary slots 18 and secondary slots 20 are made through surface 12 and opposite surface 16 in such a manner as to intersect the insertion opening 14 at a pitch of, for example, 1.25 mm. The insertion opening 14 has tapered surfaces 22, 24, and 26 at the surface 12 in order to facilitate the insertion of the FFC. At one end of the insulating housing 10, two corners are tapered to make surfaces 28, 28 for the purposes of polarity discrimination. As shown in Fig. 3, contact 40 comprises a J-shaped connecting section 44, and a stabilizer 46 extending upward from base section 42, and a soldering tail 48 (48') extending from base section 42 downward or to the side. Connecting section 44 and stabilizer 46 are inserted respectively in the primary slots 18 and secondary slots 20 of the insulating housing 10, and base section 42 straddles primary and secondary slots 18, 20. A pair of protrusions 50, 50 made in the base section 42 are pressed in the inner wall of the insulating housing 10. Stabilizer 46 has a bead 52 formed in it for the purpose of securing the position of the contact 40 and the direction of the connecting section 44 by being pressed against the inner wall of the secondary slot 20. The free end 54 of the J-shaped connecting section 44 protrudes inside the insertion opening 14 and forms a contact for connection to the FFC. Free ends 54, 54' of adjacent contacts 40, 40' are positioned at different levels in the direction of the FFC insertion (for staggered arrangement). This arrangement makes it possible to reduce the force required for the insertion of FFC. Soldering tails 48, 48' of adjacent contacts 40, 40' are also staggered, in order to simplify their attachment to the base board (not shown in the Figure). Fig. 4 represents a cross section of the connector shown in Fig. 1 in a state when the FFC is being inserted into the connector. Fig. 5 represents a cross section of the connector shown in Fig. 1 in a state after the FFC has been inserted and a pulling out force is applied to the cable. In Fig. 4, FFC 4 is inserted in the insertion opening 14 to overcome elastic resistance of the J-shaped connecting sections 44 thus deflecting them towards the inner wall 30. It is important to indicate that during the insertion of the FFC, back surfaces 56 of connecting sections 44 do not touch the inner walls 30 of the primary slots 18. Due to the fact that back surfaces 56 do not touch inner walls 30 and that free ends 54, 54' of the connecting sections are staggered, FFC 4 can be inserted in the insertion opening 14 with a relatively low resistance. Since free ends 54, 54' which come in contact with the conductors 6 of the FFC 4 are slightly rounded, they do not damage conductors 6 of the FFC 4. Fig. 5 depicts the status when an external force F is applied to the FFC 4 to pull it out of the connector 1. This causes free ends 54 of connecting sections 44 of contacts 40 to turn counterclockwise and to bend towards the inner wall 30 of the primary slots 18 so that back side 56 of the connecting section 44 comes against the inner wall 30. Due to the resistance produced by the contact between this inner wall 30 and the back surface 56, FFC 4 becomes affected by a strong frictional resistance developed between the free end 54 of the connecting section and the other wall 32 of the primary slot 18. As a result, the FFC 4 cannot be easily pulled out of the connector 1. Therefore, the retention strength of FCC 4 in connector 1 is greatly improved. Fig. 6 represents another embodiment of the connector for flat cables according to this invention. Contacts 60 of connector 1' for flat cables differ from the contacts 40 at their free ends 64. Other parts of the contacts are the same as in the contacts 40. Below, the parts of these contacts that are the same as in the contacts 40 will be designated by the same numbers. The free ends 64 are different from the free ends 54 in that their portion extending downward is longer. The portions 65 which are the same as in the free ends 54 are intended to make an electrical contact with the conductors 6 when the FFC 4 is inserted in the connector. The positions of the contact 60 and the free end 64, shown in Fig. 6, are when the FFC 4 is not inserted in the connector. The free ends 64 are made elongated in order to increase the retaining force of the FFC 4 even more, and to protect the connecting section of the contact 60. The free ends 54 of the contacts 40 in the previous embodiment provide sufficient retaining force to the FFC 4. However, if the force pulling the FFC 4 out of the connector exceeds a certain limit, the free ends 54 may be deformed in the direction of the pulling force. As a result, the free ends 54 will be bent upward and away from the surface 12 of the insulating housing 10. In the case of the contact 60, the free ends 64 are not deformed as in the previous case, thus providing a high retention strength over a long period of time. That is, when the protrusions 65 are pulled upward, as shown in Fig. 6, while the back surface 56 of the contact 60 is pressed against the inner wall 30, the contacting surface 66 of the free end 64 starts to rotate clockwise and comes in contact with the FFC 4. As a result, the upward movement of the protrusions 65 is blocked, and the FFC 4 becomes securely retained in the insulating housing 10. Above, detailed explanations concerning a connector for flat cables according to this invention has been provided. This invention is not limited to the described embodiments only and may be changed or modified depending on specific requirements or circumstances. For example, the soldering tails can extend downwards or in the direction opposite to the one shown in the above embodiments. Soldering tails can also be of the SMT (surface mounting technology) type rather than the DIP type shown in the above embodiments. It is also possible to provide posts on the insulating housing to index its position relative to the base board. Further, it is possible to incorporate in the insulating housing, the key device described in the Japanese Utility Model Application 4 (1992)-23928. The main advantage of the connectors for flat cables according to this invention resides in the fact that they provide a high retention of the cable in the connector without any additional structural elements. Since there is no need to use sliders for securing the flat cable in the connector, they have fewer parts, are cheaper in production, and are easier in installation.

Claims: An electrical connector (1,1') for an electrical cable, comprising an insulating housing (10) with an opening (14) for receiving the electrical cable (4) and slots (18,20) for receiving electrical contacts, and at least one electrical contact (40) having a connecting section (44) projecting from a base section (42), said connecting section being received in one of the slots (18) and having an end portion (56) comprising a free end portion (54,64) directed back towards the base section and into the opening (14) for contacting the cable, characterised in that the contact (40) includes a stabilizing section (46) projecting from the base section (42) and inserted into another slot (20) in order to secure the base section with respect to the housing (10), and in that the connecting section (44) extends into said one slot (18) in spaced relation with an inner wall (30) thereof and is resiliently deflectable such that, upon insertion of the electrical cable (4) into the opening (14) in the housing (10), said resilient connecting section (44) is engageable at its free end portion (54,64) with the electrical cable (4) and is deflectable in a direction away from said cable and, upon attempted separation of the cable from the housing, said end portion (56) of the resilient connecting section is engageable at the same time with said inner wall (30) and the electrical cable (4) thereby resisting removal of the electrical cable (4) from the housing (10). The electrical connector of claim 1, wherein the stabilizing section (46) has a proximal end which joins the stabilizing section to the base section (42) of the contact, and a distal end opposite said proximal end, said stabilizing section being rigid in the plane of said contact between said ends. The electrical contact of claim 1 or 2, wherein the resilient connecting section (44) is generally J-shaped. The electrical connector of claim 1, 2 or 3, wherein the resilient connecting section (44) includes at least two deflectable portions (44,54,64) separated by an acute angle bend and for deflection when said cable is in the inserted position.

Inventors: TANIGAWA JUNICHI, TANIGAWA, JUNICHI
Applicants: WHITAKER CORP, THE WHITAKER CORPORATION
Application year: 1994
Main classification: H01R9
IPC codes: H01R12